Touch sensor panels can be fabricated as one or more thin films deposited and patterned into conductive traces upon one or both sides of a chemically strengthened sheet of glass. However, standard thin film processing equipment does not allow for thin film deposition on custom-sized or shaped sheets of glass. Instead, thin film deposition occurs on large, rectangular sheets of glass (called mother sheets) which are subsequently separated and shaped into a plurality of individual glass sheets. The individual sheets are typically used in separate electronic devices.
When the mother sheet is separated into individual sheets, however, a new set of edges is formed along each path of separation. Because the new set of edges has not been chemically treated, the individual sheets are susceptible to cracking.
Techniques for chemically strengthening glass require immersion of the sheet into a chemical treatment for a certain period of time and at a certain temperature. In many cases, chemically strengthening the edges is infeasible since the exposed film would be damaged by the chemicals and/or the temperature required for the treatment.